This is an application for a K08 award for Dr. Maurice Garcia, a urologist at the University of California, San Francisco. Dr. Garcia is establishing himself as a young investigator in translational research in the area of reproductive medicine and technologies. This K08 award will provide Dr. Garcia with the support necessary to accomplish the following goals: (1) to become expert in the use of the mouse embryo transfer model and study of preimplantation embryo quality; (2) to further develop a promising technology, OET (Optoelectronic Tweezers), for clinical application in assisted reproductive medicine as well as for broader research applications; (3) to become expert in the use of mouse cognitive function assays, particularly as a means of assessing whether in vitro manipulation results in harm; (4) to implement advanced biostatistical methods in basic research studies of development outcomes; and (5) to develop an independent research career. To achieve these goals, Dr. Garcia has assembled a mentoring team comprised of a primary mentor, Dr. Deepak Srivastava, a leading expert in the field of mouse embryonic stem cells, embryo transfer and stem cell models; co-mentor Dr. Susan Fisher, who research focuses on preimplantation embryo development, survival, and placental development; Dr. Nino Devidze, an expert in mouse cognitive/motor function assays; Dr. Marcelle Cedars, a leading researcher in human reproductive medicine and technologies; and Dr. John Boscardin, an expert in state-of-the-art biostatistical analysis methods and study design. Our current limited ability to predict in vitro embryo quality is a well-recognized source of limited IVF success and adverse outcomes. Dr. Garcia's research will focus on use of OET to predict in vitro mouse embryo quality and outcomes after uterine transfer. Based (only) on their response to OET assay, he will identify which, among otherwise indistinguishable blastocyst-stage embryos, are most and least likely to result in healthy live birth following transfer (Aim 1). Then, using quantitative cellular and gene expression assays, he will define what differences in blastocyst embryo cell number and allocation, apoptosis, differentiation status, and gene expression exist among embryos stratified by the OET assay (Aim 2). In this aim, he will also study how the latter observed differences account for the embryo's net dielectric response to the OET (assay) field. Dr. Garcia will also assess whether the OET assay also predicts for differences in cognitive and motor function among young and adult mice resulting from embryos stratified by OET assay before uterine transfer in Aim 1 (Aim 3). An important additional component of all three aims is to assess whether the OET assay itself is harmful to embryos. To do so, non-OET exposed embryo control groups will be used in all 3 aims. This research will form the basis for subsequent studies utilizing more diverse outcome measures to account for the predictive value of OET assay and to evaluate for potentially harmful effects of the assay itself in order to guide refinement of the assay, to be proposed in an R01 grant application before the end of the K award.